Protective system



June 17, 1930. J BRE|$KY 1,764,385

. PROTECTIVE SYSTEM Filed July 27. 19,26

WITNESSES INVENTOR M John MBrezlsky jg BY Patented June 17, 1 930 PATENT OFFICE UNITED STATES JOHN V. BREIS KY OI' PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA circuit under predetermined conditions, saidmeans including an electro-ionictube and a contact device associated therewith for recti'-.

fying and controlling the magnitude of the current through theoperating coil of the interrupter. b

Another object of my invention is to provide, in connectionwith a relay-controlled automatic circuit interrupter, means for con-f trolling the operating current for the circuitinterrupter and for limiting the current traversing the relay contact members.

" the operation of the interrupter.

A further object of my invention is to provide, in connection with a relay-controlled automatic circuit-interru ter, f improved means for securing a defin te-time delay'in For a better understandingof my inven: tion, reference should be had to theaccom= panying drawin s, in which:

Figurel is a iagrammatic view of a protective system including an over-current relay and circuit-interrupter embodying my invention; and

Fig. 2 is a'similar view of a pol hase circuit-interrupter responsive to di erent electrical conditions embodying my invention.

Referring to Fig. I, an electrical circuit 1 is shown having a circuit-interrupter 2 therein adapted to be controlled by a tripping coil 3 upon the occurrence of predetermined electrica'l conditions. ,in the circuit. In'accordance with my invention, the energization, of the tripping coil3 is controlled by-the current transformer 4-, an electromagnetic relay 5 and an electro-ionic device fi connected t0 the relay .5 through an auxiliary transformer 30 and the tripping coil 3. 4

The electromagnetic relay 5 is provided with an actuating winding 7 connected to the terminals of the secondary winding of the current transformer! and with cooperating contact members 8 controlled bythe actuat-v ing winding 7. An auxiliary rela 9 is connected to the contact 8 o the relay 1920. Serial no. 125.144.

5 and is adapted, when operated, to close a shunt circuit around the contact members 8. T e electro-ionic tube 6 may be of the ther ionic or'heated cathode type as shown, and comprises an envelope in which the fila- -mentary cathode 10 and anodes 11 are disposed. The envelope may be exhausted or ma be filled with an inert gas, such as neon or argon... Furthermore, the filamentary cathode-shown may be replaced by other forms of electron-emitting cathodes, which are wellknown, or the device 6 may be replaced by other electro-ionic current-controlling devices having similar characteristics.

An auxiliarytransformer' 30 is interposed between the current transformer 4 and the cathode and anodecircuit s of the electroionic tube 6. The transformer 30 comprises three legs on which windings 31-, 32 and 33 are disposed. 'The winding 31 is connected HEISSUED across the current transformer 4 in series with the contact members 8. of therelay 5. The winding 32 is connected'in series with the tripping coil 3 of the circuit-interrupter 2 and the anodes and cathode of the electroionic device 6. As shown, the device 6 comprises two anodes 11 arranged to rovide full w ave rectification of the current t rough the tripping coil 3. The windin 33 is connected to the cathode 10 of the e ectro-ionic.

device 6 and may be restricted in cross sec current to a safe value.

-'tion in order to limit the cathode-heating .i- If the circuitl is traversed by an excessive current, the; over-current relay 7 isoperat vely energized and closes its contact members 8, thereby closing the circuit of the cathode 10 of the electroionic tube 6. After a definite time delay, which is required for the cathode 10 to reach the electron-emitting temperature, a current is established in the ano the tripping coil 3 is operatively energized to o en the circuit-interrupter 2. e time delay may be made small or even substantially eliminated if desired by reducing the mass of the cathode or increasing the filament current.

In some cases," a definite time delay in the operationof a circuit-interrupter is desired e circuit of the electro-ionic tube 6 and 1 introduce a time delay in the operation of the circuit-interrupter, an additional time element is obtained or the relay 5 ma be an instantaneousrelay, such as the solenoid type. If the relay 5 is an instantaneous relay and the electro-ionictubeis instantaneously operative, as would be the case if the cathode 10 is of small mass "or normally at or near the electron-emitting temperature, there is no time element in the operation of the circuitg interrupter.

When the contact members 8 ofthe relay 5 engage, the relay 9 becomes energized and closes a shunt circuit around the contact members 8until the circuit-interrupter 2 operates. The operation of'the circuit-interrupter is therefore independent of chattering of the contact members 8 and the contact members are not required to interrupt the heating current of the cathode 10. The elec-v tro-ionic device 6 serves not only to providea definite minimum time delay, where a time delayis desirable, in the operation of the circuit-interrupter 2' but also rectifies the eurrentthrough the trippin coil 3 so that an ordmary direct-current tripping coil may be used. I

- In many instances it is desirable to vary the time adjustment of the circuit-interrupter in order to secure the selective operation of several circuit-interrupters connected in se-.

ries or for some other purpose. In such systems, the disconnection of only the faulty section is obtained by increasing the time element of the circuit-interrupter nearest the station. This is accomplished in the system which I have described as indicated above by either changing the time adjustment of the over-current relay 5, by increasing the thermal lag of the cathode 10, as by increasw ing its mass or by delaying the increase of anpde or cathode potential to the operating va ue.

' It will be apparent that the system which I have described has several advantages over 5 pluor systems. A sensitive auxiliary relay may be employed in connection with the electro-ionic tube and the tube limits the current P through the contact members of the relay to prevent injuring the same. Furthermore, the

m electro-ion'ic tube not only provides a definite minimum time delay in the o ration of the clrcult-interrupter but by rectifying-the tripping current, improves the operation of the tripping coil when energized directly from an alternating-current circuit.

The principles of my invention may be applied to polyphase circuits and to other forms of contact devices or protective relays. For example, in Fig. 2 I have shown a threephase circuit 15 having a circuit-interrupter 7 16 therein provided with a tripping coil 17. The energization of the tripping coil 17 is controlled as before by current transformers 18 and 19, a relay 20 and an electro-ionic device 21.

The current transformers 18 and 19 are connected in separate phases of the circuit and a network 22 is connected between. said current transformers and the actuating windof the relay 20 so that the relay is energ0 glzed, for example, in proportion to the posi tive phase-sequence component of current in the circuit 15. An auxiliary transformer 23 is provided having a magnetizable core member 24 on the three legs of which the wind- 35 ings 25, 26 and 27 are disposed.

The windin 25 of the auxiliary transformer is connecte to the current transformers 18 and 19. The winding 26 is connected in series with the cathode 10 of the electro-ionic device 21 and the contact members 28 of the relay 20. The winding 27 is connected in series with the tripping coil 17 in the anode circuit of the electro-ionic device 21. This arrangement rmits the anode potential to be selected in ependently of the potential ap plied to the cathode and to be changed without altering the cathode potential. The leg of the transformer 23 on which the winding 26 is disposed, may be so restricted in cross- 7 section, as indicated, as to become magnetically saturated in order to limit the current traversing the cathode 10 and the contact members 28 of the relay 20.

When the positive phase-sequence component of current in the circuit 15 exceeds a predetermined value, the relay 20 is riperatively energized and closes the circuit 0 the oathode 10 of the electro-ionic device 21. After a time delay required to heat the cathode 10 to the electron-emitting temperature, a current traverses the anode circuit of the electroionic device 21 and the tripping coil 17 of the circuit-interrupter 16 is operatively energized, thereby opening the circuit.

I have shown difierent modifications of my invention in order to illustrate the primerples thereof more clearly. Various other modifications within the scope of my invention will occur to those skilled in the art and therefore I'desire that my invention shall not be limited in scope except as indicated 1n the a pended claims.

. I c aim as my invention:

;' 1. In an electrical circuit having a circu1t 126 interrupter therein and an actuating winding therefor, a thermionic device having an anode and a cathode, a transformer core having a winding thereon for energization in accordance with an electrical condition in said cir- 130 ing on another leg of said core for energizing said cathode and means embodied in 881d leg for limiting the energization of said cathode, and a winding on the third leg of said core for energizing the actuating winding of said interrupter through a circuit including said anode and cathode in series relation.

, 3. In an electrical circuit having a circuit interrupter therein and an actuating winding therefor, a thermionic device having an anode and a cathode, a transformer core having a winding thereon for energization in accordance with an electrical condition in said circuit, a second winding on said core for energizing said cathode, means for limiting the energization thereof, and a third windin on said core for energizing the actuating wlnding of said interrupter through a circuit including the anode and cathode of said thermionic device, and means operable in response to a predetermined condition on said circuit for controlling the operation of said thermionic device.

4. Ina polyphase electric circuit having a I circuit interrupter and an actuating winding therefor, a thermionic device having a cathode and an anode, a transformer core having a winding thereon and means for energizing said windings in accordance with the current traversing said circuit, a second winding on said core for energizin said cathode, a third winding on said core or energizing the actuating winding of said interrupter through a circuit including said anode and cathode in series relation, and means responsive to the phase-sequence characteristics of said circuit for controlling the energization of said ther- Inionic device.

In testimony whereof, I have hereunto subscribed my name this 17th day of July,

JOHN V. BREISKY. 

